LeetCode63. 不同路径 II
作者:互联网
class Solution { public int uniquePathsWithObstacles(int[][] obstacleGrid) { int m = obstacleGrid.length, n = obstacleGrid[0].length; // dp[i][j] 表示 (0,0) 到 (i,j)的路径总数 int[][] dp = new int[m][n]; if (obstacleGrid[0][0] == 1) return 0; for (int i = 0; i < m; i++) { for (int j = 0; j < n; j++) { // (i,j)本身有障碍物,则任何路径都到达不了,dp[i][j] = 0 if (obstacleGrid[i][j] == 1) { continue; } if (i == 0 && j == 0) { dp[i][j] = 1; }else if (i == 0) { dp[0][j] = dp[0][j-1]; }else if (j == 0) { dp[i][0] = dp[i-1][0]; }else { // (i,j)只能由(i-1,j)和(i,j-1)走到。 dp[i][j] = dp[i-1][j] + dp[i][j-1]; } } } return dp[m-1][n-1]; /** * 优化:滚动数组。 */ /* int m = obstacleGrid.length, n = obstacleGrid[0].length; // 一维数组即可,按行更新。 int[] dp = new int[n]; for (int i = 0; i < m; i++) { for (int j = 0; j < n; j++) { if (obstacleGrid[i][j] == 1) { dp[j] = 0; continue; } if (i == 0 && j == 0) { dp[0] = 1; }else if (j != 0){ dp[j] += dp[j-1]; } } } return dp[n-1]; */ } }
标签:LeetCode63,obstacleGrid,int,路径,else,II,++,length,dp 来源: https://www.cnblogs.com/HuangYJ/p/14217088.html